Motor-control system.



{YE-ST AVAILABLE COP.

No. 808,778. 'P'ATBNTED- JAN. 2, 1906. w. B. POTTER.

MOTOR oomno SYSTEM.

APPLIGAT ION FILED AUG. 10. 1904.

"m e/7f0.r William BPQTET. I y &1;

' tension alternating current isreduced to a Io a/ll whon'ait-mayconcern:

UNlgbED STATES Be it known that I, WILLIAM B POTTER, a citizenof theUnitedStates, residing at Schenect'adyucounty' of Schenectady; State ofNew York, have invented certain new and useful "Improvements inMotor-Gontrol Systems, of

l which the following is a specification.

My invention relates tothe control of electrical vehicles driven bymotors adapted for operationon both direct frents. re 1 v I It-"i's'sometimes desirable to employ a hightension alternating current over aportion of -}the'le'"ngth of an electric railwayas, for in} stance, inthe'countryor over private rights 'of- -way and to" employ low tensiondirect an alternatingcurcurrcntoverother portions, asWithin theconfi'nes of cities. -Gertai n types of motorsa s, for instance, thewell-known series moto r maybe designed for operation on eitheralternating or direct current. The voltage which may with impunity beimpressed upon such alternating-current motors is very much lower thanthe' voltage which may advantageously bee-impressed upon a,direct-current motor. Thus whilefor ordinary railway-work the di-. rectcu'rrent supply is about six'hundred volts the alternating-currentvoltage which may be efiiciently employed is only about twoh-undred, atwhich point ditficulties in commutationb'egin to arise, Line-currentscannotbe efficiently employed at so Iowa direct-current voltageas thatto which,altern'ating current motors are limited. Although itis'diflicult to design such motors foroperation on six hundred voltsalternating current, it is quite prac}. ti'c'able to so designthem that.they will operate successfully andelficiently ontwo hundred voltsalternating current and three hundred volts direct cu rrent.Consequently if the highvoltage'of about four-hundred by means vof atransformer then by connecting two such mo- .tors to operate in seriesthe equipment is adapt-z I "Spbcificati on of Letters Patent.Application filed August 10, 1904. SerialNo. 220,161.

BEST AVAlLABLE COP, v

i rATE T- oFrIoE.

B.- ror'rna, o1?" IJSOHEN'ECTADY, NEwYoRK, Asslenon roenn- QQ RAL ELEorRoooMPAN A CORPORATION or NEW YORK,

l i I l ,.MCV)VTORCQNTBOL}SY STEM. i

Patented Jan. 2, 1906.

former, the tranformer being of course cut out of circuit when themotors are connected directly to the trolley for'receiving directcurrent.. Y

The above-mentioned changein circuits is not all that is'required in asystem of this character, for the reason that if a series motor isdesigned for operation on a system of alternating-current voltage and isthen connected to a direct-current source pfthe same voltage the motorwill 'be heavily overloaded, since the motor then possesses noself-induction and theentire impressed voltage must be balanced by thecounter electromotive force developed in the mo'tor-a-rmatu re that is,both the current flow and the speed will increase. When the direct-curren'tvoltage is not equal 'to the alternatingrcurrent voltage, but isgreateras, for instance, when two hundred volts alternating and th reehundred volts direct per motor are employedthe overload will be stillmore serious.

Consequently in chang ing from alternating to direct currents themotor-field should be strengthened so as to increase the counterelectromotive force per ampere. This may be accomplished in a simplemanner by connecting the two poles of the field in parallel foralternating current and in series for direct current. The motor systemjust described forms no part of the present invention, broadly speaking,but isset forth and-claimed in Patent N 0. 783,124, granted February 21,1905, on 'by Maurice Milch.

anapplication tiled For operating large a'nd'heavy'cars successfully andat high rates ofspeed it is necessary to employ more than two of themotors which have just beendescribed, and it is desirable inaccelerating the motors that they should first be connected all inseries, so that each motor has a low terminal voltage, and then inparallel, whereby they receive their full voltage I g One objct ot' thepresent invention is to devise an equipment of motors and controllingmeans therefor whereby the usual series and parallel motor groupingsmaybe carried out tosome extent (luring acceleration of the To this endthe presentinvcntion contemplates the arrangement ot the motors ingroups, each group comprising, preferably,

roc

two motors, and so arranging the controller that the various groupsaretreated as units which are first connected inseries with all.

, which varies the fieldstrength of the motor for varying thevoltageimpressed upon the controller.

lamps relative to-the terminal voltage of the motors.

Where the .car isprovided with a motordriven' air-compressor for anair-brake system, the same changes must be made in" the c1rcu1tconnections for this? motor.-.as-;. t h9se;; which are requiredfor thecar-motors themselves.

A further feature of my invention consists in so arranging the contactsof the switch for varying the field strength for the drivingmotors thatthe field strength of the air-compressor motor is simultaneously variedin the proper manners It is customary to employ a blow-out coil or coilsfor interrupting the arcs that may occur at thecontroller-contactsuponmaking .changes in the motor-circuits where direct current is impressedon the motors. i/Vhen not essential, particularly when the alternating-current voltage is lower than the directcurrent voltage. Moreover,a' blow-out coil energized by alternating current would have littleeffect andif lft in circuit would; re-" quire a laminated core'toobviate da'ngeifms heating. I g I A further feature of my inventionconsists .in providing means for cutting out the blowout coil or coilswhen the motors are connected for operation on alternating current.

' Other featu res of the present invention will appear in connectionwith the following description thereof. 1

In the accompanying drawing I haveshown diagrammatically one systembywhi'ch the present invention may be carried out; but it is of courseunderstood that the details of the arrangement illustrated may be variedin-many ways without changing the character of'the invention. Similarreference characters will be used to denote corresponding elementsthroughout the specification and in the drawing.

The particular form of system illustrated 1s one adapted for afour-motor equipment,

In this way the lamp voltage may be maintained constant whether themotors are operating on direct or alternating current,

alternating current is used, a blow-out coil is and M, M M and Mrepresent the four driving-motors of the car arranged in two groups ofmotors, each connected in series. By means of the series connection theterminal voltage ofth e motors is made only half the voltage of themotor-circuit,'and by transforming .the alternating-current line voltagedown to approximately four hundred volts them'otor can be designed torun eificiently both on alternating-current. and under the ordinarydirect-current line voltage.

Grepresents a controlling-switch for the motors arranged to connect thetwo groups of motors in series and in parallel and to regulate theamount of resistancel which is included in the motor-circuit.

B represents the usual blow-out coil for the it indicates thereversing-switch?by means of'which the relative connections of fieldsand armatu res may be reversed in order to reverse the direction ofmovement of the car or other vehicle. The field of each motor is shownas divided into two parts, which are connected to .theswitch E, which Ishall hereinafter call the co'i'n'mutating switch, and which acts toconnect the two'portions of the field either in series or in parallel,accdrdingas the impressed current is direct or'altern ating. Thecommutating' switch E also serves to connect the motors and thecontrolling-switch C to the secondary of the transformer T or to theswitch D, according to the positionin which the commutating switch isplaced. The primary'of transformer T' isconnected to switch A.

T represents the trolley or othersource of current, which is connectedboth-toswitch D and to the switch A. It is seen, therefore,

that if switchrD is closed trolley T is connected directly through thecommutating switch Etc the motor-circuits, while ifswitch A' is closedthe trolley is connected through the primary of the transformer toearth.

Theswitch'es A and D are preferably mounted upon a'single handleorotherwiseinterlocked, so that when'one is closed the other cannot beclosed,.bi1t must remain open. This construction is representeddiagrammatically in the drawing, but forms no part of the presentinventiomit being, set forth and claimed in an application filed byJesse. S.

Peve'ar, Serial No. 220,l 66,--filed on the 10th day of August, 1904.

A fuse a/ and a lightning-arrester a of any usual or preferred forms areadapted on the alternating" current voltage and a fuse d,lightning-arrester d and choke-coil d are adapted for-use on the dii*ectcurrent voltage.

on represents an aufiiliarymotor for driving an air compressor, and"this motor is also connected to contacts on-th'ejcommut'ating switch E,

g and 8' represent, respectively, a governor for the motor in andasw'itch wherebythe circuit of the motor'mmay he opened or closed.

" erate nndersubstaintially-the-w'hole impressed selectromotivefio'reinz'the"circltitiefith motor-to prevent over-- other terminal the switchbisclosedg thereby opening switch -and conniecting trolley T to contact'6 of the commutatidg switch ;';-assurne also that the commutati ngsinitch is in the position to bring 5 gagement veithi'tiieistationarycontact-fingers,'; w andassnmefi turti ier'; that reversing-switch R ris in its forward. positionth at is with the movable con'tact cn theline f and 9:7 in;en

-to contact t thacontacte through lamps Land 1 -heating-coilsiH,through'a portion of com- "55 v ing-coi ls are h'usconnected directly betweenva line and 'thegrouniithe portion of the com-- nameiy iro m sgvgjtchDcontact 6, contact 5 motoris thus connected across the line with thecircuitterrniriaifot whichisconnected to the g Commntating switchEandthe-other terminal "siredconstruction, the various circuits needwhile an-interrnediate'tap-is connected to the Now-let;thecontrolling-switch C be movedto itsfirst positiom -as in'dicated bythefirst dot The 'con'tact. 1

"d contact tigz resistancel, contacts f? 1, contacts fifandg'fifiiarmatu re of motor M, arma-I ture of ino'to Miebntactsf and fcontacts :'series;-

turther'current may be traced as seer AVA Since this' motorm -1s' sn1alland operates only .:fcuit therewith; As the controller is moved tointermittentlydt is possible to design it to op- A resistance 'r isplaced- -L=represefits iafn ps,% and H heating-coils, one

The fi the 'compensator t is connected to a cent-act onithecommutatingswitch,

to one terminates th'e compensator t.

. The operation is as -follows:- Assume that the movabie 'cdiillacts onthe line dd into engagementaei thr-the -stationary contact-.fi ngers.

- circuits are now as followsz" zswi'te -LDFcontact 6, contact "e,orrtaot e :blow'+out coil B, cont/act oi"- motors M ancli Mflcontacts.e,contact '6,-

ppe rhalves of'the fields of moamass f =-andf through armatactsf and fthrough the lower halves of "---:Themotors are therefore connected ail=in senieswith each other, with the two -pm ticins off the field of eachmotor in follows: starting from switch D and passingpensator ftp g ioundl- The lamps and heatpensatoi? t havtnfgnp 'efl'ect, since the caris opdirect current; ,It' switch 8 is closed, a stiilfifflathef circuitmaybe tracedtwo portions of its field in series. The-circuits justdescribed are those when the controller is in ts first-running position,the motors being connected in series with all resistance in cirthe"drawings.

Jnected to the direct-current source.

iLABLE COP and-through its successive running positions -=in"'-th'eusual manner the resistance I is cut out w stepby step until the twomotors remain con- -nec'ted rin parallel with no resistance -.incireuitis-r Since this is the usual manner in which acceleration of themotors is produced and :sinc'e't-he 'niotor-controller maybe of an y. de

not be traced in detail, but are evldent from 1f it is now desired torun the motors on alternating current, the switch -D isopened, thecommutating switch E is moved to the position in which the movablecontacts'on the line a a are brought into en gagement with thestationary contact members,-and then the switch A is closed. Thus thetrolley T is connected directly to the primary of transformer T.Starting now from the right-hand terminal of the secondary oftransformer T, the motor-circuit is asfollows: contact e e, contact 6contact 6 contact 0', contact 0*, resistancel, contacts f f,

contacts f and f, through the armature of motor M, armature of motor Mcontacts f and f-,*contacts f and ff.

divides, part passing'through contact 0 con- Here the" cur- I tact-e,and the upper halves oflthefields of thefields' of'rnotors M and M",contacte contact e,to theground. It is seen that the motors are nowconnected in series with eachother with all the resistance in. circuit,but

with the parts of each field in parallel with each other. It will alsobe noticed that no branch of the circuit passes through blow-outcoil B,which is therefore now idle. The compensator t has itsleft-hand terminalconnectedto the right-hand terminalof the secondary winding oftransformer T and has its intermediate tap'gronnded. The terminalvoltage 'of the compensator t is consequently greater :-than=-that ofthe secondary of transformer T', and therefore-if the compensatortisproperly proportioned the lampsL, which are connect- ;ed across theterminals of the'compens'ator through contacts el and e, will besupplied with the same voltage as when they were conan armature of motorm. Here thecurrent The cir- IIG 1 and the other portion passing throughcontact compressor-motor as those which-were made readily be designed-towithstand any desired voltage. WhatIclaim as #5 j -"plying'aiternatingor direct current to said motors, a--switch adapted."to connect said i iin series and in parallel, and aswitch for varying the field strength-ofthe motors; 3.]In combination, a plurality of .groups'of director-alternating cu rren't toeaid. motors,

.a switch-for connecting-said groups in series 1 and in parallel'and,for'v'arying the amount of- '."producing a relative -variation=" in thefield strength of the motors'when running ondirect and-on alternatingcurrent;

v and in paralleland-fordetermining of-resistance in the motor-circuit.

:01 the vehicle, to anism is adapted to cha field connec' ,motors, each"group comprising a-plurality of motors permanently connected 1n serles,said the amountof resistance'in the motor-circuit,

-. 2:. In combination, a plurality of groups of -oralternating=current,means for supplying as.

motors adapted for operation on either direct 1 or alternating current,-and,meansfor supplying direct or alternatingcurrent to-saidmotoconnect. the source'of current to said mo,- tors and tothe primary ofsaid transformer seer Ai/AiL-QBLE COP;

divides-part passing through the left-hand portionof the' field, contact6' to the ground 9, contact 0 right-hand halves'of motor-field toground. ,The same changes have therefore been effected in-the fieldconnections of the in the field connections of the driving-motors By thepresent system a single switch m'eclitions for both the driving and theauxiliary motors, and the arrangement is such that the only switchessubject to high-potential strain when the car is running onalternatingcurrent are thes'witches' D and A, which may I new, anddesire to secure by Letters Patent .ofthe United States, is.,

1. -I n. combination, a plurality of groups of motors being adapted foroperation on either .direct' or alternating current, means for sup-.

groups in series and in parallel and to vary and witch adapted'to varythe fieldstrength of the motors. 1

motors adapted for operation on either direct alternating currentordirect current to said. motors,-a-switch fortconnectmg said groupsmotors adapted vfor operation on either direct or alternatingcurrent,flm eansj for supplying resistance in the motor-circuit, andmeans'for 4. In combinationa piurality of groups of respectively, and athird switch adapted to "vary the field strength of the motors and toconnect said motbrsto the secondary of said transformer. 6. In avehicle, driving-motors therefor, an auxiliary motor, all of said motorsbeing adapted for operation on alternating 'o'rdirect current, means forconnecting the motors for operation on alternating or direct current,and

a switch adapted to connect portions of the "fieldsof all the motorsinjseries and in parallel.

7; In a vehicle, driving-motors therefor adapted for operation onalternating or direct current, means for supplying the motors withalternating and d irectcurrents of different voltages, lamps connectedin shunt to thepoWer-circuit, a voltage-changing device, and means forconnecting said device in the lampcircuit when the motors are connectedfor op- "eration on alternating current.

8. In a vehicle, drivingmotors therefor adapted for operation on-director alternating current, means forsupplying direct and al-.

ternating current of different voltages to said motors, avoltage-compensatorhaving a point on? its winding intermediate itsterminals grounded, a lamp-circuit having one terminal connect-ed; tothe source and the other to;one terminal of said cotnpensatorgand meansfor connecting the. other terminal of said compensatorto the'soiircewhen the motors are connected for operation on'alternating currents.

9. In a vehicle, driving motors therefor adapted for operation onalternatingor direct current, means for supplying the motors withalternating and dirct currents of different voltages, lamps connectedin'shunt to the -power'-circui t, a voltage-changing device, and

aswitch for decreasing the fieldstrength of the motors and includingsaid compensating coil in the nating current. A

10. In combination, a plurality of motors adapted for operation oneither alternating or' foo lamp-circuit foro'p'eration on alterdirectcurrent,' a controlling-switchfor said motors, a bl'ovv-out coiltherefor, andmeans for=cutting said corl'outof c rcuit when the motorsare c'onnected for operation on alternatingcurr'ent.

11.- In combination, a' 'plurality of motors adapted for operation oneither alternating'er'" direct current, a controlling-switch for said-motors, a blow-out coil-therefor, and a switch arranged to'vary' thefield' strength of the motors and to out said co'i'h'out of circuit.

In witness whereof lfhave hereunto set my v .vvILLIA-M B.' P0TTER.-Witnes s es: I

' BENJAMIN B, HULL,

MARGARET E. WOOLLEY.

